Different types of yarn | yarn properties and definition of yarn

SLUB YARNS:- The consumers desire for ornamental effects has  Popularized the production of yarns that are given only a small amount of drawing out. Such yarns, called SLUB YARNS, have soft, untwisted areas at frequent intervals throughout their length. They are coarse, with slight twist, having varying diameters that show irregularities typical of an incomplete spinning operation If simulation of linen is desired, the use of slub yarns is easily understood. Where durability is a main consideration, their practicability is justly questioned, because a heavy yarn protruding above the level of surrounding yarns is subjected to friction and the fabric soon shows signs of wear at those
points after continued use. In the past, slub yarns were generally used in fabrics that possessed an especially compact construction and consequently were characterized by marked durability. To day slub yarns do not always imply compact construction in the fabric of which they are a part. They furnish ornamental effects and are often used for that purpose in shantung and tweed.

  
FLAKE YARNS:- Flake yarns are variations of slub yarns. The flake or slub effect is made by inserting soft,thick tufts of roving between binder yarns at intervals. The result is a flake yarn of varying thickness and softness, caused by the soft-effect ply held in place by the uniform binder. This type of yarn is also limited to fancy-effect uses.

SPIRAL YARNS:- The general appearance of a spiral yarn is that of a coarse yarn wound around a fine yarn, giving the effect of a spiral. The thicker  yarn is given a slack twist and wound spirally around the fine yarn (sometimes referred to as the CORE YARN), which is given a hard twist . Other names for the spiral yarns are CORK-SCREW and ECCENTRIC . Spiral yarns may be made for different purposes. They may be constructed in such a way as to give the decorative spiral effect of a candy-cane pattern. Sometimes the core yarn is completely hidden by the spiraling outer yarn, as in the case of Latex where the core  yarn is rubber while the outer yarn may be of cotton, nylon or other textile.

STRETCH YARNS:- Textured yarns that have been programmed for extra-ordinary extensibility are stretch yarns. Most stretch yarn can be extended from one and one-half to twice their normal or relaxed length; some can be extended three or four  multiples of their relaxed length. These structures are not only highly extensible but highly elastic as well. The term highly elastic is used here to suggest a quick and practically complete recovery toward original yarn geometry or configuration after substantial extension in the direction of the yarn axis. In their relaxed state, stretch yarns resemble high-bulk yarns. On extension of the stretched yarns, however, the bulkiness is considerably reduced. At full extension, the stretch yarn resembles an ordinary continuous filament yarn, combination or staple yarn, whichever may be the parent yarn or precursor. Most stretch yarns are made by texturizing the thermoplastic continuous filament yarns. Texturizing brings about considerable nonlinearity or crimp in the individual filaments. This nonlinear configuration of the filaments is heat set for permanency but not entangled as in the case of the high-bulk yarns. Consequently, the stretch yarn extends and recovers as the filaments collectively straighten and recoil. This phenomenon is very similar to the action of a coiled spring. In addition to the afro mentioned advantages, stretch yarns

provide cling without great pressure and good covering power in fabrics. However, the tactile qualities are not as good as high-bulk or staple yarn. Also some serious disadvantages, such as filament snagging are associated with stretch yarns. Examples of some stretch yarn geometries are shown in the subsequent figure. The methods of inducing stretch and the degree and character of stretch vary considerably among these yarns. Stretch yarns should not be confused with rubber or elastomeric fiber yarns; they are normally used in power stretch fabrics where more than a subtle pressure is required. These heavy duty elastomeric yarns are not as widely applicable as stretch yarns and therefore are considered to be special end-use yarns.
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